Dual-mode capable wireless telecommunications networks permit wireless telephone subscribers to access the wireless network using either analog or digital radio telephones. In order to permit wireless communication using both analog cellular telephones and digital cellular telephones, dual-mode networks must be equipped with both analog and digital radios at every receiving station. Typically, each cell, or sector, within a dual-mode wireless network is equipped with both analog and digital radios at each receiving station to handle both types of signals.
When a wireless subscriber accesses a dual-mode wireless network using an analog radio telephone, the call is completed through an analog radio located at the nearest receiving station if an analog radio channel is available. If no analog communication channels are available at the receiving station, the subscriber is "blocked" from completing a call, and a long busy signal is played to the subscriber indicating that no call-handling capacity is currently available. The subscriber is then forced to hang up and to retry the call until an analog channel becomes available at the receiving station to handle the communication. If subscribers are frequently blocked in this manner, subscribers may become dissatisfied with their wireless service provider. Therefore, wireless service providers seek to provide enough analog radios to supply a sufficient number of analog radio channels so that subscribers are not frequently blocked.
When a subscriber accesses a dual-mode wireless network using a digital radio telephone, the call is completed through a digital radio located at the receiving station if a digital radio channel is available. However, if a digital channel is not available at the receiving station, the subscriber using a digital radio telephone is not "blocked" like the subscriber using an analog radio telephone. Rather, the communication from the subscriber using the digital radio telephone will "overflow" onto an analog radio channel if one is available. This is possible because most digital cellular telephones are capable of operating in both digital and analog modes. Therefore, if a digital radio channel is unavailable to handle the call, the call overflows onto an available analog channel.
If no analog or digital channels are available, the subscriber using the digital radio telephone will be blocked from completing the call. As discussed above, frequent call blocking is undesirable because it may frustrate wireless subscribers. The number of analog and digital radios installed in each sector throughout a dual-mode wireless network must therefore be chosen in a manner so as to provide enough radio channels to minimize call blocking. The number of analog and digital radios must also be chosen to minimize the total number of radios so that equipment costs may be kept low.
The number of analog and digital radios installed in a sector of a dual-mode wireless network is, in general, determined based upon predicted offered analog and digital loads. Typically, an estimate is made of the amount of digital and analog communication traffic that will be received in a given cell, or sector. The number of analog and digital radios necessary for the cell may then be calculated with several factors influencing the calculation. First, as described above, the total number of analog and digital radios should be chosen so as to minimize blocking. Second, the number of digital radios should be maximized because wireless subscribers prefer digital sound and because digital is a more efficient communications medium than analog. Third, the total number of analog and digital radios should be minimized so as to keep costs low for the wireless service provider while ensuring that wireless service can be provided at a competitive price.
Accordingly, there is a need for determining the number of analog and digital radios in a dual-mode wireless network that provides sufficient call-handling capacity so that call blocking is minimized, while also minimizing the total number of cellular radios. There is also a need for determining the number of analog and digital cellular radios in a dual-mode wireless network that maximizes the number of digital cellular radios and minimizes the number of analog cellular radios.